Editorial: Induction and Maintenance of Long-Term Immunological Memory Following Infection or Vaccination

Stability analysis of SEIR model related to efficiency of vaccines for COVID-19 situation

This work is aimed to formulate and analyze a mathematical modeling, SEIR model, for COVID-19 with the main parameters of vaccination rate, effectiveness of prophylactic and therapeutic vaccines. Global and local stability of the model are investigated and also numerical simulation. Local stability of equilibrium points are classified. A Lyapunov function is constructed to analyze global stability of the disease-free equilibrium. The simulation part is based on two situations, the US and India. In the US circumstance, the result shows that with the rate of vaccination 0.1% per day of the US population and at least 20% effectiveness of both prophylactic and therapeutic vaccines, the reproductive numbers R0 are reduced from 2.99 (no vaccine) to less than 1. The same result happens in India case where the maximum reproductive number R0 in this case is 3.38. To achieve the same infected level of both countries, the simulation shows that with the same vaccine's efficiency the US needs a higher vaccination rate per day. Without vaccines for this pandemic, the model shows that a few percentages of the populations will suffering from the disease in the long term.